Apparatus for burning pulverized fuel



May 20; 1930. v. z. CARACRISTI APPARATUS FOR BURNING PULVERIZED'FUELFiled May 6, 1921 6 Sheets-Shet IN VEN TOR.

ATTORNEYS.

May 20, 1930. v. z. CARACRISTI APPARATUS FOR BURNING PULVERIZED FUELFiled May 6, 1921 6 Sheets-Sheet May 20, 1930. I v. z. CARACRISTI1,759,033.

' APPARATUS FCR BURNING PULVERIZED FUEL Filed May 6, 1921 6 Sheets-Sheet4 ATTORNEYS.

May 20, 1930. v. 27 cARAcRlsTl APPARATUS FOR BURNING PULVERIZED FUELFiled May 6, 1921 6 Shee s-Sheet INVENTOR. Wd mw' sj ATTORNEYS.

May 20, 1930. v. z. CARACRISTI 1,759,038

APPARATUS FOR BURNING PULVERIZED FUEL Filed May 6, 1.921 6 Sheets-Sheet6 ATTORNEYS Patented May 20, 1930 UNITED STATES VIRGINIUS Z. CARAORISTI,OF BRONXVILLE, NEW YORK, ASSIGNOR 'IO COMBUSTION ENGINEERINGCORPORATION, A

PATENT OFFICE CORPORATION OF NEW YORK V APPARATUS FOR BURNINGIP'O'LVEBIZED FUEL Application filed May 6, 1921. Serial No. 457,345.

This invention relates to an apparatus for burning pulverized fueland isparticularly useful in the generation of steam.

It has for one of its objects the eflicient burning of a given quantityof pulverized fuel in less time and in a smaller furnace than heretoforepractical. As another ob ect my invention is intend d to reduce den 7areas to a minimum, 1. e. to utilize full furnace space to bestadvantage. i

A further object is to make an efiicient applioation of; pulverized fuelto a boiler such as the Ladd type.

Still another object is to provide a novel and improved arrangement ofash pit, combustion chamber, boiler and stack, tending to procuresimplicity in'construction, opera-. tion and maintenance.

- My invention also contemplates an improved arrangement for simpl andeifectively carrying on the pulverizmg, separating and deliveringoperations, especially where there is a battery of boilers. I

he foregoing, together with such other ob'ects as may hereinafter appearor are incij cut to my mvention, I attain by means of;

a method and apparatus, the preferred embodiments of which areillustrated in the accompanying drawings, wherein:

Fig. l is an end elevation of a battery of boilers embodying myinvention, the furnace, boiler setting, and associated structure for oneboiler being in section as indicated by the line 1-1 in F1 3.

Fig. 2 shows a f ragmentary section taken as indicated by the line 2--2in Figs. 1' and 3, on a larger scale.

Fig. 3 is a somewhat diagrammatic plan view of a portion of aninstallation, parts above the section line 33 in Fig. 1 being brokenaway and removed.

Figs. 4 and 5 illustrate an installatlon embodying my invention inmodified form ;'F1g. 4 being an end elevation similar to Fig. 1, andFig. 5 a plan view with parts above the section line 55 in Fig. 4 brokenaway and removed. I

Fig. 6 is a more or less diagrammatic section taken substantially on theline 6-6 of Fig. 1 and illustrates the conveyor arrangement I employ,with only those parts shown which are directly associated with theconveyors.

Figs. 7, 8 and 9 are enlarged fragmentary sections taken on the lines77, 8-8, and 9 9, respectively, of Fig. 6.

Referring now to Figs. 1 to 3 inclusive, it will be seen that I havetherein illustrated a battery of furnaces A arranged to provideintermediate or central and end lon 'tudinal bays B, G, D and transversebays F, etc., between furnaces.

A description of the furnace shown in section in Fig. 1 will suffice forall furnaces. The furnace, starting from the bottom, consists of an ashpit 7, located on the ash and pulverizer fioorS, and having door 9 forash removal as by a vacuum system such as indicated at 10; a combustionchamber 11 above the ash pit and opening at the top into a boiler space12 located in the boiler setting or chamber thereabove; the boilerelements, consist- .ing of the upper drums at, b, o and the lower drums(Z, (Z, with connecting banks of tubes 6, f, 9, 7t, inclined sharplytoward the vertical; and the stack 13, located above the boiler space,and communicating therewith at the top of each of two opposite sides bymeans of the forked conduit-14. The banks of tubes are baffled in anypreferred manner as indicated at 15.

The combustion chamber is fired from each of two opposite sides by meansof a plurality of burners 16. coal being supplied thereto in a manner tobe hereinafter described. The burners maybe of any desired construction.Pulverize'd'coal "or a mixture of coal and air is fed into the furnacepreferably in a substantially vertical downward direction, additionalair being supplied. through. the burner by induction and the balanceneeded for combustion through a group of openings 17 in the opposingfront walls of the combustion chamber. The incoming streams are ignitedby the radiant heat from the respective. front walls and the draughtturns the streams back on themselves, the two upwardly moving portionsof the fuel and flame streams uniting at the central portion of thecombustion chamber. As the fuel particles become progressively gasified,the stream broadens because of increased volume, so as to practicallyfill the upper portions of the combustion chamber, which is of such sizeas to obtain substantially complete combustion therein. The hot gases ofcombustion sweep along the tubes and upwardly toward the center and thendivide, part being drawn along the right hand tubes toward the draughtoutlet on that side of the boiler space and the remainder being drawnalong the other tubes to the draught outlet on the opposite side.

The fuel and flame streams are preferably turned above the bottom of thecombustion chamber to provide a cooling zone below the zone ofcombustion, through which the slag forming refuse not carried insuspension precipitates. In passing through this zone, such refuse coolsbelow substantial slag forming tem erature. The ash deposit is dustlikeor flake-like in character, susceptible of easy removal without shuttingdown.

From what has been described it will be seen that I take the fuelnecessary to operate a furnace of given size and capacity at any givenrate and divide it into streams admitted on opposite sides of thecombustion chamber, as a result of which there is less coal per streamthan would be otherwise the case, and thus, firstly, there is obtained agreater area of exposure for the fuel particles both to radiant heat andair; secondly, there is greater opportunity for each particle to besurrounded by air; thirdly, as the fuel particles begin to gasify andfresh quantities of oxygen bearing air are needed for the furthercombustion of the particles and for the combustion of the volumes ofcombustible gases released or distilled off, such fresh air is morereadily available; and fourthly, the turning streams are reeiprocablysubjected to one anothers radiant heat. As a result of these conditions,ignition takes place more quickly and combustion is completed in ashorter interval of time and more coal can be burned in a furnace ofgiven size. Greater efiiciency is thus obtained and it is possible togreatly exceed the normal rating of a given sized furnace. In addition,a. greater pro ortion of the combustion chamber is made e ective and thehot gases can be more effectively delivered to the absorption surfacesfor heat transfer.

Referring now to the manner of treating and handling the coal, it willbe seen that I provide crushed coal bins 18 in the upper part of thecentral bay B, and the pulverizers 19 in the bottom thereof on the floor8, the pipes 20 serving to feed the crushed coal to the pulverizers.Below the crushedcoal bins I arrange a pair of pulverized coal bins 522for each furnaces burners,to which latterthe pulverized coal is suppliedby the feeder mechanism 21 which may be of any preferred type. In theouter bays C and D I place other pulverized coal bins 22, arranged onthe sides of the combustion chambers opposite the pulverized coal bins22. The pulverized coal is taken from the pulverizers and elevated tothe dust collectors or separators 24 by air, by means of the motorexhausters 25 and pipes 26. The pipes 23 are the air return pipes,carrying back the air after separation has been effected. The members 27are additional dust collectors. The pulverized coal is discharged fromthe separators into the conveyors 28 and 29 running lengthwise of thetransverse bays C, D, from which it is discharged to the pulverized coalbins 252* through suitable discharge openings 28" having suitable gates(not shown).

Pulverized coal is delivered to the bins '22 from the pairs of conveyors28-29 by the pairs of conveyors 303l running longitudinally of the bay13, delivery from conveyors 2829 to conveyors 3031 being made by crossconveyors 3233.

It will be seen from the foregoing that at each intersection of atransverse bay with the central longitudinal bay B there are fourpulverizers, each of which normally supplies a respective pair of bins9.2" and 22, the former being supplied from the separators thru themedium of conveyors 28 and 29 and the latter through the medium ofconveyors 28-29, cross conveyors 3233, and conveyors 30-31. In case afurnace is shut down its pulverized coal bins become filled andthereafter the pulverized coal is conveyed to the next bin which isempty or only partially filled or which is feeding for it will readilybe understood that when a bin becomes filled, the coal must necessarilybe carried past by the conveyors.

All of the pairs of conveyors are oppositely acting, so that in case anypulverizer goes out of action temporarily, pulverized coal can besupplied from another pulverizer from an opposite direction by closingthe gate or gates from the conveyor normally supplied by the inactiveconveyor and open ing the gates from the other conveyor. Variousdelivery combinations are possible by this arrangement.

The whole supply system is thus very flexible and at the same time verysimple and economical in spaceand also in power requirements.

Referring now to the modification shown in Figs. 4 and 5, this conformsin all substantial respects to what has previously been described, savethat the pulverized coal bins of the central longitudinal bay aredifferently supplied. In this modification I have illustrated a batteryof furnaces A arranged to provide longitudinal bays B G I) andtransverse bays E F etc. ,between furnaces. The furnaces shown eachinclude an ash pit 7 having door gr for removal of ashes as by vacuumsystem 10, the ash pit being located on the ash and pulverizer floor 8;a vconibustion chamber 11", opening into a boiler space 12 thereabove;the upper and lower drums of the boiler element being indicated byreference letters a, b, c and d and a stack 13 located above the boilerspace.

Burners 16 are provided for the furnace which operate as described inconnection with Figs. 1, 2 and 3.

For'treating and handling the coal I provide crushed coal bins 18 andpulverizers 19 on the floor 8 the pipes 20 serving to feed the crushedcoal tothe pulverizers. Below the bins 18 I arrange pairs of coal bins22for each respective set of burners and feeder mechanism. In the outerbays C and D I place other pulverized coal bins 22. The

pulverized coal is taken from the pulverizers and elevated to the dustcollectors or separators 24. by air by means of the exhausters 25 andpipes 26. The pipes 23 are air return pipes. The pulverized coal isdischarged from separators 24? into the conveyors 28 and 29 runninglengthwise of the transverse bays C and D from which it is discharged tothe pulverized coal bins 22 as described in connection with Figs. 1,Qand 3.

In this instance, however, there are two additional pulverizers 19 atthe main intersections, each of which delivers to separators 24: locatedin the central bay and adapted to discharge into the respective pairs ofconveyors 80 -31. Additional dust collectors are indicated by thereference character 27*.

It will be seen from the foregoing that bins 22 are supplied from thepulverizers 19, separators 24 and pairs of conveyors 28 and 29 while thebins 25% are supplied from the pulverizer 19", separators 24c and pairsof conveyors 3031.

The location of the separators at an upper level in position todischarge by gravityis also a simplification as it permits of the use ofthe air used in effecting separation as the means for elevating thepulverized coal, thus eliminating elevating conveyors.

No specific claim is made to the furnace structure per se, as claimsdirected thereto have been made part of the subject matter of adivisional application Serial No. 72;47, filed December 1, 1925.

\V'hat I claim is:

1. In a pulverized fuel burnlng system for power plants, the combinationof a pair of furnaces spaced apart to provide a bay therebetween andincluding combustion chambers,

said furnaces occupying a substantial porizer below thepulverized coalbin, means'for delivering coal from the coal bin to the pulverizer, andmeans whereby coal may be delivered from the pulverizer to thepulverized coal bin.

2. In a pulverized fuel burning system, the combination of a pair ofdouble fronted furnaces arranged to provide a central bay betweenfurnaces and an outer bay at the other front of each furnace, each ofsaid furnaces including a combustion chamber, a coal bin in the uperpart of the central bay, a pulverized coal bin therebelow, feeder meansfor feeding pulverized coal from said pulverized coal bin to one of saidcombustion cham bars, a pulverizer below said pulverized coal bin,conveyor means leading from the coal bin to. the pulverizer, apulverized coal bin in each outer bay, means for supplying pulverizedcoal thereto from the pulverizer, an a feeder means for supplyingpulverized coal from said last mentioned pulverized coal bins to acombustion chamber.

3. In a pulverized fuel burning system, the combination of a pair ofdouble fronted furnaces, arranged to provide a central bay betweenfurnaces and an outer bay at the other front of each furnace, each ofsaid furnaces including a combustion chamber,

a coal bin in the upper part of the central bay, a pulverized coal bintherebelow, feeder means for feeding pulverized coal from saidpulverized coal bin to one of said combustion chambers, a pulvcrizerbelow said pulverized coal bin, conveyor means leading from the coal binto the pulverizer, a pulverized coal bin in each outer bay, a feederconnection from each thereof to a combustion chamber, separator means, aconnection between the pulverizer and separator means, and means forsupplying pulverized coal from the separator to the various pulverizedcoal bins.

4. In a pulverized fuel burning system, the combination of a pair ofdouble fronted furnaces arranged to provide a central bay betweenfurnaces and an outer bay at the other front of each furnace, each ofsaid furnaces including a combustion chamber, a coal bin in the upperpart of the central bay, a pulverized coal bin therebelow, feeder meansfor feeding pulverized coal from said pulverized coal bin to one of saidcombustion chambers, a pulverizer below said pulverized coal bin,conveyor means leading from the coal bin to the pulverizer, a pulverizedcoal bin in each outer bay, a separator in each outer bay, means forsupplying pulverized coal thereto from the pulverizer, and conveyormechanism for supplying pulverized coal to the various pulverized coalbins from the separators.

5. In a powdered fuel combustion system, the combination of a furnace,at pulverized fuel bunker, means for feeding coal from said hunker tothe furnace, a green coal bunker located above the level of saidpowdered fuel bunker, and coal treating, apparatus through'which thecoal is fed from said green coal bunker to said pulverized fuel bunker,said apparatus including treating units to which the coal is fed bygravity from said green coal bunker.

In testimony whereof, I have hereunto signed my name.

VIRGINIUS Z. OARAORISTI.

